The invention relates to a motion sensor or a device for detecting positional changes.
Motion sensors of the type under consideration are capable of detecting positional changes along at least two axes of a three-dimensional coordinate system. These motion sensors are used on movable objects such as, for instance, passenger cars, which are stationary at times. The motion sensors generally include a weight, a transmission and a unit for sensing changes in position.
A motion sensor of this kind can be employed for various purposes, e.g., antitheft purposes. In such a case, the motion sensor is fixed to an object to be protected and activated when necessary. By way of example, if the object to be protected is a car, the motion sensor is activated upon leaving the car after parking. When the motion sensor is in its activated state and the object to be protected is moved out of its resting position, an acoustical or optical signal is generated so that unauthorized used can be detected immediately.
In many situations, the use of such motion sensors is made more difficult by special conditions. For instance, antitheft systems for cars must have low weight, small dimensions and absolute functional reliability, must be insensitive to climate and dust, must use little energy, and must be capable of being installed in any position.